A. Field of the Invention
The present invention relates to an endoscope having a fluid supply tube with a branch section, an image guide, a light guide, and some other components.
B. Description of the Prior Art
A typical endoscope is disclosed in, for example, Japanese Patent Disclosure (KOKAI) No. 60-63814. This endoscope is provided with an operation section, an insertion section, and a light-guiding cable. The insertion section has a flexible tube, and a bendable tube, and a distal-end unit. The distal-end unit has through holes. In these holes, an air/water supply nozzle, an objective lens, an illumination lens, and the like, are accommodated. The proximal end portion of the air/water supply nozzle is fitted in the first through hole, and is connected to one end of a connection tube. The other end of the connection tube is coupled to the distal end of an air/water supply tube, which is flexible. Branch pipe is provided, which comprises two inlet portions and one outlet portion connected to the flexible tube. The proximal end of the air/water supply tube is coupled to the outlet portion of the branch pipe. The first inlet portion is coupled to a flexible, air-supply tube, and the second inlet portion is coupled to a flexible, water-supply tube.
A first connection pipe is connected to the distal end of an image guide. The first connection pipe and the objective lens are fitted in the second through hole formed in the distal-end unit. The distal end of a protective tube protecting the image guide is fastened to the first connection pipe. The protective tube is provided within the bendable tube, and its proximal end is opened.
A second connection pipe is provided within the third through hole of the distal-end unit. The illumination lens and the light guide, aligned coaxially, are fitted in one end portion of the second connection pipe. The distal end of a protective tube protecting the light guide is fastened to the second connection pipe. This protective tube is provided within the bendable tube, and its proximal end is opened.
The conventional endoscope described above has a drawback. When the operation section is operated, thus bending the bendable tube, the distal end portions of the protective tubes protecting the image guide and light guide abut against the branch pipe, inevitably bending and buckling both the image guide and the light guide. Consequently, the affected tissue or the region of interest within a body cavity cannot be seen, and a correct diagnosis cannot be made.